It is known to use a constant relative vacuum source connected via a high fluid flow impedance to a cavity sealed on or in a component or structure to monitor for impending faults. Such systems are for example described in U.S. Pat. No. 6,539,776; U.S. Pat. No. 6,591,661; U.S. Pat. No. 6,715,365 and U.S. Pat. No. 6,720,882 all assigned to the present applicant; and U.S. Pat. No. 5,770,794 (assigned to Tulip Bay Pty Ltd).
In the claims of this application and in the description of the invention, except where the context requires otherwise due to express language or necessary implication, the words “comprise” or variations such as “comprises” or “comprising” are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
It is to be understood that any references to any prior art publication in this specification does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.